A simple idea solidly executed is what bite-size gaming is all about. "Bullet Trap" uses one stick for shooting and the other for shield, restricts your movement to a few specific nodes, and then tells you to kill a bunch of baddies. All of which would be about as entertaining as "Robotron" with a broken left stick, except that this game’s titular innovation is that your bullets bounce off walls, and they’ll damage you as much as the enemies.
This upends the first rule of the twin-stick shooter: Always Be Firing. Instead of just pushing the right stick in every direction all the time, you have to be aware that every missed shot is going to become a new problem. You can plan your strategy around firing only in the direction you're shielding (that left stick will become your best friend), but the shots can go at unpredictable angles, and your enemies are shooting too, which means each level builds to some serious panic. Worse yet, the harder you fight, the more danger you're in, since frantic shooting just creates more danger.
There's quite a few levels in the game, and each tweaks the rules and enemy behavior in unpredictable ways, so you won't get bored even after you've gotten the hang of the mechanics; I wish more full-length titles had this many variations on their basic gameplay. Along with a fun single-player game, there's a co-op mode guaranteed to end some friendships when a bad shot bounces back, and of course, a versus mode.
"Bullet Trap" proves that a simple switch in underlying principles can breath a lot of life into a genre. Twin-stick shooters are badly overrepresented on the Xbox 360, but "Bullet Trap" proves there’s always room for a good idea.